The present invention relates to a door swinging device for automatically opening and closing doors, and more particularly relates to a link mechanism of such door swinging device.
FIGS. 1 and 2 illustrate a typical example of the conventional door swinging device, in which 1 designates a door operator attached to a header of a door supporting frame 2 or a wall above the door supporting frame 2. The door operator 1 is provided with an electric motor (not shown). A rotating shaft 3 which is operatively connected to the electric motor projects downwards through the casing of the door operator 1. A rotating arm 4 is attached at its one end to the rotating shaft 3 so as to rotate in a horizontal plane, and is pivotably connected at the other end to one end of a connecting arm 5, the other end of which is pivotally connected to a bracket member 6 which is fixed to and projects from an upper portion of a door 7 hinged to a jamb of the door supporting frame 2 so as to be swingable about a vertical axis. The rotating arm 4, connecting arm 5 and bracket member 6 forms a door swinging link mechanism.
When the rotating shaft 3 is angularly moved in the direction A or clockwise in FIG. 2, the rotating arm 4 is turned in the same direction, which causes the door 7 to be swung and opened through the connecting arm 5 and the bracket member 6 to a position shown by the phantom line in FIG. 2. In this prior art door swinging device, it is necessary to project a rather large length of bracket 6 from the door 7 in order to effectively swing it. Thus, for example, when the door 7 is, as shown in FIG. 2, provided transversely of a passage way, the door 7 cannot be fully opened unless a recess 9 for receiving the bracket 6 and the connecting arm 5 is, as shown, formed in the side wall 8 since the bracket 6 abuts against the side wall 8. The side wall 8 is deteriorated in the strength and appearance by the presence of the recess 9.